In recent years, with high data transmission speed desired for various electronic apparatuses, high-speed serial transmission, such as Peripheral Component Interconnect (PCI)-Express or Universal Serial Bus (USB) 3.0, is widely spread. In the high-speed serial transmission, in order to transmit a signal by high speed, a subsequent signal is changed and transmitted before the level of the signal becomes stable. For this reason, even in a digital circuit, a signal to be transmitted behaves as an analog signal.
Factors, which cause the quality of a signal (signal waveform) to be transmitted to be deteriorated, include transmission loss in which the signal to be transmitted is attenuated, reflective noise which is generated in a position in which impedance is discontinuous, and the like. In recent years, it has become possible to perform high-precision transmission waveform simulation (high-speed digital signal transmission simulation) in which the factors are taken into consideration by combining an electromagnetic field analysis tool and signal analysis.
Japanese Laid-open Patent Publication No. 2003-216676, Japanese Laid-open Patent Publication No. 2004-184301, and Japanese Laid-open Patent Publication No. 2005-107870 are examples of the related art.
In contrast, even in a case of a Printed Circuit Board (PCB) of the same design, there are production variations in elements, which are arranged on the PCB, production variations in substrates, and the like. With the refinement of an integrated circuit, such as a Large Scale Integration (LSI), and a high data transmission speed, the influence of variations in various elements on the transmission line of the PCB on a quality of a transmission signal is growing every year.
For this reason, the number of combinations of the variations to be considered when the PCB or the like is designed is enormous. However, it is difficult to control variations in an actual machine, and thus it is difficult to verify phenomena for the respective combinations of the variations in the actual machine.
Therefore, a technique of verifying the quality of a received waveform based on various variations using simulation is important. However, the number of combinations of variations to be considered is enormous, and thus it is difficult to perform verification on the whole combinations within actual design turnaround time (TAT) based on waveform analysis (simulation).
Here, under the circumstances, some combinations of variations are manually extracted from an enormous number of combinations of variations and verification is performed on the some extracted combinations. However, in such verification, verification omission is generated, and thus there is a possibility that failures occur in the actual machine due to a combination which is not extracted.
An object of the embodiment disclosed in the specification is to verify the quality of a signal waveform in a short time, even when the number of combinations of variations in a verification target is large.